Pigments Ensure Excellent Moldability
Non-crystalline polylactic acid starts to soften above 60°C. In crystalline form, however, it resists softening even above 60°C. For this reason, the material must undergo crystallization before it can be used in electrical appliances. Unfortunately, the crystallization of polylactic acid is a time-consuming process that also reduces moldability and productivity. However, Sony discovered that the crystallization process could be dramatically accelerated through the addition of pigments, such as copper phthalocyanine. By adding these substances as crystallization accelerants, Sony was able to achieve a molding cycle of around 30 seconds, which is the same as conventional plastics. This discovery dramatically enhanced the suitability of Sony's vegetable-based plastics for mass-production, since it meant that they could be molded in the same injection molding systems used for conventional plastics.
The Ideal Renewable Material
The carbon materials used in vegetable-based materials are derived from plants, which absorb carbon dioxide from the atmosphere. This means that even if vegetable-based plastics are burned, only atmospheric carbon dioxide that had been fixed by plants is released, and there is no increase in carbon dioxide in terms of the total cycle. In that sense, vegetable-based plastics are an ideal renewable material. Increased use of vegetable-based plastics will help to reduce oil consumption and lower total greenhouse gas emissions.
The aluminum hydroxide added to vegetable-based plastics is safe for humans. In fact it is used in toothpaste. The other additives of vegetable-based plastics are mainly derived from vegetable-based materials. Vegetable-based plastics currently account for 55% of plastics used in Sony products. Sony plans to take the initiative in further research and development relating to vegetable-based plastics. It also intends to use these materials in its products.
